1. Field of the Invention
This invention relates to energy radiation devices for medical hyperthermic treatments and, more particularly, to a combined catheter and energy applicator for treating prostatomegaly such as benign prostatic hypertrophy, prostatitis, and prostate malignancy.
2. State of the Art
Hyperthermia or induced high body temperature has been considered beneficial in treating various human diseases including many types of cancer. More specifically, various types of malignant growths are considered by many researchers to have a relatively narrow hyperthermia treatment temperature range. Below a threshold temperature of about 41.5 degrees Celsius, thermal destruction of these malignancies is generally not possible, and may even stimulate their growth. However, at temperatures above a range of about 43 to 45 degrees Celsius, thermal damage to most normal body tissue cells occurs if exposure lasts for even a relatively short duration.
While some types of superficial cancers are known to respond to direct application of surface heat, deeply located or subsurface malignant growths, owing to limited penetration depth of externally applied energy, tissue blood flow, and heat transfer properties of the body, are more difficult to heat to the desired temperature without damaging overlying and adjacent healthy tissue. A solution to this problem has been the development of radiation heating devices for inducing hyperthermia. This form of treatment is historically known as xe2x80x9cdiathermia.xe2x80x9d
Radiation heating of subsurface growths from an exterior surface using, for example, electromagnetic (EM) or ultrasound (US) radiation, is ordinarily enabled by the configuration and placement of one or more applicators and by appropriate selection of EM or US radiation frequency, phase and intensity. Nevertheless, tissue growths inside of, or in close proximity to, heat sensitive tissue or organs, are much more effectively and safely heated by radiation irradiating applicators positioned within the body as close as possible to the growth requiring treatment.
The advantages of positioning radiation applicators relatively close to the growth to be heated by radiation include more direct treatment of the enlarged tissues causing the undesirable symptoms. It also permits improved heating control, more localized heating, and consequently less possibility of overheating adjacent healthy tissue.
Close applicator access to certain types of diseased tissue growth may be provided by surgical procedures for naturally occurring body passages such as the esophagus, larynx, urethra, prostate gland and colon. Surgical procedures may enlarge the passage by cutting away the diseased tissue. Some heating methods use small radiation applicators placed over the tissue or in an incision to provide direct irradiation of the growth.
Special and difficult problems often attend growths found along natural body passages. For example, diseased tissue tends to spread around and along the passage, often in a relatively thin layer. Typically, patient problems may originate from a tissue layer which is less than one centimeter thick, and may extend as far as 6-10 centimeters along the passage. Care must be taken to avoid the use of applicators which may result in nonuniform radiation heating of the elongated growth. To make one end of the applicator hot enough to kill the unwanted elongated growth, it may be necessary to make the temperature at the other end of the applicator so hot that it may kill surrounding healthy tissue. To treat a longer tissue along the urethra or other passage, multiple treatments of short, adjacent lengths of tissue may be necessary with the antenna manually repositioned along the urethra between each treatment.
Attempts to properly position the applicator in proximity to the targeted tissue include the use of balloon catheters, which utilize pressurized fluid to inflate the balloon in the neck of the bladder, thereby positioning and maintaining the applicator at a desired position in proximity to the targeted tissue. A lack of a reliable method to determine the position of the applicator and whether the applicator has moved during the treatment may result in inconsistent treatment results or unwanted heating of healthy tissue. Consequently, care must be taken to insure that the applicator remains at the desired position in response to deflation of the balloon or other movement of the catheter.
Accordingly, it is an object of the invention to provide an improved energy radiation device for medical hyperthermic treatment.
Another object of the invention is to provide an urethral insertable energy applicator for treating benign prostatic hyperplasia or other tissue diseases associated with the urinary tract.
A further object of the invention is to provide an urethral insertable energy applicator which can be positioned with respect to the prostate and maintained against movement therefrom during treatment.
A more specific object of the invention is to provide a system for determining whether the energy applicator has moved or may move during treatment and to signal the operator and/or deactivate a power source in response to such conditions. A related object is to provide an urethral insertable energy applicator for treating BPH which includes a system for determining whether conditions exist in which the applicator may move during treatment and signal the operator of such conditions.